A variety of products such as gowns, sheets, drapes, instruments, etc. which are required during surgery, or other aseptic procedures, are used on a daily basis in the normal operation of hospitals, clinics and the like. Where such products are not pre-packaged in a sterile state, it is necessary for the hospital or clinic to sterilize them before use. Furthermore, where these products are not disposable, and are employed more than once, it is necessary that they be cleaned and otherwise prepared for subsequent use. Prior to such use, however, it is essential that such products be sterilized.
Due to the volume of materials involved, it is often necessary to sterilize and store these products for use as desired. Accordingly, there has been developed a procedure where such products, after cleaning, laundering and the like, are packaged in cloth sterilization wrappers for subsequent use, and the wrapped package is then sterilized and stored. As may be apparent, there is a potential danger in such a procedure. There is a prospect of unsterilized packages becoming mixed with sterilized packages when stored for use.
To prevent unsterilized products from being used by the physician or attendant requiring sterile materials, various types of sterility indicators which are attached to, or incorporated into, the wrapped sterilization package have been developed. This permits a user to immediately determine whether a particular package has been passed through the sterilizer. Although such sterilization indicators have, in many instances, been placed in the wrapped package or attached to the wrapped package, the most convenient way of applying such sterilization indicators is to have the sterilization indicators carried by pressure sensitive adhesive indicator tapes used for holding the cloth wrapper in a closed position prior to, during, and after sterilization of the enclosed products.
Various pressure sensitive adhesives have been used with tape backings that include appropriate color changing means to indicate if the package has been exposed to sterilization conditions. Examples of pressure sensitive adhesives employed with such indicator tapes include water insoluble natural rubber based adhesives, natural rubber and synthetic rubber blend adhesives, styrene-isoprene-styrene block copolymers with tackifying resins, vinyl ethers, and high molecular weight acrylate copolymers having minimal amounts of plasticizing monomers included therein. See e.g., U.S. Pat. Nos. 2,889,799, 3,067,057, 3,078,182, 3,311,084, and 4,188,437. Typically, these indicator tapes use a paper, fabric or film backing, and an adhesive chemistry that is resistant to softening upon exposure to heat.
Cloth sterilization wrappers may be disposed or retained after use. If retained, the soiled cloth wrappers must be cleaned after use, usually by laundering in soapy water, such as an aqueous alkali solution. These wrappers will then be used to wrap items to be sterilized. The expense of some cloth wrappers, such as treated synthetic wrappers and untreated wrappers, demands that the closure and sterilization indicator tapes not damage the wrapper after use.
The various indicator tapes referenced above are not formulated to disperse during cleaning, and in fact, if not manually removed before laundering, may permanently damage a sterilization wrapper. Specifically, the heat and chemicals associated with laundering and drying of the sterilization wrappers will cause the pressure sensitive adhesives used with the indicator tapes to flow into the fabric of the cloth wrappers, and thereby permanently damage the sterilization wrapper.
Water-dispersible pressure sensitive adhesives have been made and used for paper making and printing operations which require splicing of the end of one roll of paper to the beginning of another roll. For example, U.S. Pat. Nos. 3,865,770, 4,413,080, 4,569,960, 3,441,430, and 2,838,421 disclose such water-dispersible pressure sensitive adhesives and/or splicing tapes made therefrom. Further examples of water-soluble or water-dispersible pressure sensitive adhesive compositions, and/or tapes made therefrom, can be found in U.S. Pat. Nos. 4,413,082, 4,341,680, 4,388,432, 3,890,292, 3,763,117, 3,152,940, 3,096,202, and European Patent Publication Nos. 0 352 442 and 0 297 451. In addition, U.S. patent application Ser. No. 07/580,116 describes an autoclavable water-dispersible pressure sensitive adhesive on a dispersible backing for use as a means to adhere cloth to cloth or cloth to skin in areas where high amounts of fluid would be present.
To date, no indicator tapes utilizing water-dispersible, pressure sensitive adhesives exist. Thus, present indicator tapes must be removed from sterilization wrappers or other garments prior to laundering to avoid permanent damage to such articles.